The use of lithium-based initiators for polymerization of conjugated vinyl compounds is well known. This usually takes place in the presence of a solvent and results in a so-called "living polymer" wherein the growing end or ends of the polymer are capped by a lithium ion. As U.S. Pat. No. 3,119,800 indicates, the living polymers may then be terminated by reaction with various alcohols.
It is also known to hydrogenate polymers by the use of Ziegler-type catalysts, or particularly the reaction products of cobalt or nickel alkanoates with aluminum reducing agents such as an aluminum trialkyl. As U.S. Pat. No. 3,644,588 shows, this reaction product may be activated by the presence of various alcohols among other weak Lewis acids.
In any commercially feasible process, it is necessary to be able to readily purify the principle desired product, in this case a polymer, and also to purify other components of the reaction mixture for recycle, primarily the solvents employed. However, the art does not effectively teach how this can be done. For example, when a lower alcohol such as isopropanol is employed as either the terminator during polymerization or as an activator for the catalyst in the hydrogenation step, it then becomes a problem to effectively separate the alcohol from the solvent employed in both of these stages for later recycle due to the relative closeness of the boiling points of the alcohol and the usual solvents utilized and the azeotrope formed between the solvent and alcohol. On the other hand, if the activator or terminator are of too high a boiling point, then it becomes virtually impossible to separate residual quantities of them from the coagulated polymer by normal processing techniques such as drying, steam sparging or the like.